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Introduction to GIS Ghassan Mikati, Ph. D GIS Expert
A computer system which can hold and use data describing places on the earth's surface.
What is GIS? GIS is: A mapping software – such as Electronic Atlas: It displays pictures of geographic areas on the computer It provides information about these areas It provides ability to alter graphics And even more than that, it has the ability: To create graphics using information database To import external information & databases To use tabular information to create charts & graphs And to analyze information statistically
Components of GIS Database Organizational Structure & People Computer Hardware & Software
Components of GIS Hardware: the computer on which GIS operates Software: which provides the functions and tools needed to store, analyze, and display geographic information. Data: geographic data & related tabular data People: GIS users who range from specialists to simple users Methods: a designed plan and business rules
Raster vs. Vector GIS works with two models: Vector: information is encoded and stored as a collection of x, y coordinates Raster: comprises a collection of grid cells
GIS Layers GIS stores information about the world as a collection of thematic layers that can be linked together by geography
On a Map… Every object is called Map Feature… Roads Park River
Geographic Features Geographic features are represented by two types of data. Street Name Address range on left Address range on right Length to travel Directions to travel SPATIAL DATA ATTRIBUTE DATA
On a Map… Map features are represented as points, lines or areas… Sites as points Roads as lines Park & River as areas
Related Information… GIS stores all descriptive information about features as attributes in a GIS database. Each column stores a different attribute Each row relates to a single feature
The Map/Table link Any change in the attribute table is reflected on the map.
The Map/Table link
Features & Attributes Sets of features and attributes together are called themes: Buildings Parks River Roads
GIS Database All themes together make the GIS database Roads Buildings Parks River
On a Map… Map scale controls the size of features and shapes used to represent them, i. e. when map scale increases, so does the size of the map feature. City as point Building as polygon Roads as lines Roads as polygon
Getting Answers to Questions With GIS we can: Get information about features Find features based on their attributes Analyze features locations
Here we are seeking to find out what exists at a particular location. A location can be described in many different ways using, for example, place name, or latitude and longitude coordinates
Identifier: 565 -88 -221 Area: Owner: Address: Zoned land use: Assessment: 108, 900, 245 John Morris 3233 Texas St. Industrial $950, 000
Getting other types of information about a feature
Instead of identifying what exists at a given location, you want to find a location where certain conditions are satisfied. For example, you wish to find a house assessed at less than $200, 000 with 4 bedrooms and made of wood.
Find features based on attributes they share Result Map 4 Bedrooms More than a certain area Within a certain price
This seeks to discover the differences between an area as the result of the passing of time.
City in 1950 City in 1990
This seeks to discover what types of patterns may exist in the newly created data file that were not visible before. For example you may wish to know where motor vehicle accidents occur and at what times.
What kinds of patterns exist for motor vehicle accidents? Where do they occur and at what times?
GIS locates features with regards to their location to each other: Features adjacent to… Features within a certain distance Features within a certain area Etc…
Looking for an apartment within 0. 5 km from high school Schools High School Apartments for sale within 0. 5 km
Major Areas of Practical Application of GIS Technology Street Network-Based vehicle routing and scheduling location analysis, site selection development of evacuation plans
Major Areas of Practical Application of GIS Technology Facilities Management • locating underground pipes, cables • balancing loads in electrical networks • planning facility maintenance • tracking energy use
Major Areas of Practical Application of GIS Technology Land Parcel-Based • • zoning, subdivision plan review land acquisition environmental impact statements water quality management
Major Areas of Practical Application of GIS Technology Natural Resource-Based • • forest management habitat, migration routes management wild and scenic rivers preservation recreation resources planning wetland preservation agricultural lands management groundwater modeling and contamination tracking